package org.bouncycastle.asn1;

import java.io.IOException;
import java.io.InputStream;

class ConstructedOctetStream extends InputStream {
    private final ASN1StreamParser _parser;

    private boolean _first = true;
    private InputStream _currentStream;

    ConstructedOctetStream(ASN1StreamParser parser) {
        _parser = parser;
    }

    public int read(byte[] b, int off, int len) throws IOException {
        if (_currentStream == null) {
            if (!_first) {
                return -1;
            }

            ASN1OctetStringParser s = (ASN1OctetStringParser) _parser
                    .readObject();

            if (s == null) {
                return -1;
            }

            _first = false;
            _currentStream = s.getOctetStream();
        }

        int totalRead = 0;

        for (;;) {
            int numRead = _currentStream.read(b, off + totalRead, len
                    - totalRead);

            if (numRead >= 0) {
                totalRead += numRead;

                if (totalRead == len) {
                    return totalRead;
                }
            } else {
                ASN1OctetStringParser aos = (ASN1OctetStringParser) _parser
                        .readObject();

                if (aos == null) {
                    _currentStream = null;
                    return totalRead < 1 ? -1 : totalRead;
                }

                _currentStream = aos.getOctetStream();
            }
        }
    }

    public int read() throws IOException {
        if (_currentStream == null) {
            if (!_first) {
                return -1;
            }

            ASN1OctetStringParser s = (ASN1OctetStringParser) _parser
                    .readObject();

            if (s == null) {
                return -1;
            }

            _first = false;
            _currentStream = s.getOctetStream();
        }

        for (;;) {
            int b = _currentStream.read();

            if (b >= 0) {
                return b;
            }

            ASN1OctetStringParser s = (ASN1OctetStringParser) _parser
                    .readObject();

            if (s == null) {
                _currentStream = null;
                return -1;
            }

            _currentStream = s.getOctetStream();
        }
    }
}
